Abstract

We have theoretically studied two mechanisms of coherent second-harmonic generation (SHG) based on the three- and the five-wave-mixing processes taking place in a chiral liquid. This coherent effect was recently observed in a non-centrosymmetric suspension of bacteriorhodopsin-bearing units of Halobacterium Halobium purple membranes [1]. Our theory agrees with the experimental evidence of arising of both the quadratic and the fourth-order (in respect of the pump-wave field) parts of the second-harmonic wave. Both SHG mechanisms considered are only possible with the use of a focused beam, not of a plane-wave pumping.

© 1998 IEEE